[ASTImporter] Various source location and range import fixes.

Summary:
ASTImporter contained wrong or missing imports of SourceLocation
and SourceRange for some objects. At least a part of such errors
is fixed now.
Source location import fixes in namespace, enum, record,
class template specialization declarations and DeclRefExpr,
UnresolvedLookupExpr, UnresolvedMemberExpr, NestedNameSpecifierLoc.

Reviewers: martong, a.sidorin, shafik

Reviewed By: shafik

Subscribers: rnkovacs, dkrupp, Szelethus, gamesh411, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D60499